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Biomedical subjects

E Toft

Publications and source records attributed to E Toft.

29 records · Page 2Linked to original sources
PubMed1989

Biomechanical properties of the human ankle in relation to passive stretch.

Viscous/plastic properties were investigated in the passive tissue opposing dorsiflexion of the human ankle. The foot was rotated (dorsiflexed) and fixed. Due to viscous/plastic properties, the passive torque declined with time. After 300 s, torque, relative to the initial torque at 0 s, had fallen by 22.7% +/- 2.6% (mean +/- 1S.D.), as an expression of the relative importance of the viscous/plastic tissue properties for the passive torque. By a peel-off technique the number of different tissue elements with viscous/plastic properties was found to be at least three. After 100 s, all but one of these elements had yielded completely. Viscous/plastic properties were unchanged by stretching when measured 90 min after a single stretching program and when measured 24 h after stretching procedures had been performed twice a day for three weeks.

Adult↗
PubMed1989

Serum and urinary phosphate during and after prolonged muscular ischaemia in non-exercising men and women.

Serum inorganic phosphate (Pi) concentrations and urinary Pi excretions were measured in nine patients undergoing abdominal aortic bypass grafting (group I) and in nine patients undergoing lower limb arterial embolectomy (group II). In group I, serum Pi concentrations were normal until 24 h after reperfusion, when they decreased, reaching their nadir at 48 h (median Pi 0.45 mmol 1(-1). The urinary phosphate clearance relative to the creatinine clearance (Cp/Cc) increased 5 min after reperfusion reaching a maximal median value (0.454) in the 2-24-h collection period. In group II, eight patients had a normal and one had a subnormal serum Pi before reperfusion. None developed hypo- or hyperphosphataemia and the Cp/Cc remained unchanged. Daily urinary Pi excretion was higher in group I than in group II (P less than 0.03). The authors concluded that the regional muscular ischaemia in non-exercising men and women was not associated with hyperphosphataemia. The possible influence of major surgery and anaesthesia on phosphate homeostasis should be considered.

Aorta, Abdominal↗
PubMed1989

Quantitation of the stretch reflex. Technical procedures and clinical applications.

The stretch reflex should ideally be quantitated for better clinical use by standardizing the muscle stretch and measuring the resulting muscle contraction. Quantitation of muscle contraction can be done by force measurements or electromyographic recordings. The electromyographic response to stretch consists of one component (short latency response) for short stretches (less than 15 ms) and of 2 or 3 components (short and long latency responses) for longer stretches (greater than 40-50 ms). The magnitude of the phasic stretch reflex is reflected by the short latency response, whereas the magnitude of the tonic stretch reflex is reflected by both the short and the long latency responses. In clinical studies of upper motor neuron syndromes, the knee jerk and the muscle tone correlated with the magnitude of the short latency response. In patients with paralysis agitans an increased long latency response, which correlated to the rigidity, was found.

Humans↗
PubMed1989

[Reflex examination. Neurophysiologic and biochemical status].

The neural network excites when a stretch reflex is elicited during a physical examination. It is important to be aware that the stretch reflex depends on the contraction level of the muscle before stretch, and on the amplitude and velocity of the muscle stretch. A changed resistance from passive tissue or muscle fibre them self has to be taken into account when evaluating the size of the stretch reflex. A weak contraction compared with no contraction in the stretched muscle decrease the variation in the size of the stretch reflex. Influence from other types of receptors and synergistic and antagonistic muscles can also contribute to the stretch reflex.

Animals↗
PubMed1988

Muscle stiffness in human ankle dorsiflexors: intrinsic and reflex components.

1. The purpose of this study was to evaluate the mechanical response to stretch in normal human ankle dorsiflexors at different levels of voluntary contraction. In an active muscle, the total mechanical response is the sum of the intrinsic response from the contractile apparatus, the response from passive tissues, and the reflex mediated response. Each of these components was investigated. 2. The total incremental stiffness was defined as the ratio between the torque increment and the amplitude of the stretch. In 14 subjects the total stiffness increased from approximately 0.6 N.m/deg to approximately 2.5 N.m/deg at 50% of MVC and remained constant (+/- 10%) from 30 to 80% of MVC. 3. The contribution to incremental stiffness from intrinsic muscle properties was measured during electrical stimulation of the deep peroneal nerve at 7-50 Hz. Intrinsic stiffness increased linearly with torque from approximately 0.5 N.m/deg to approximately 2.5 N.m/deg at 80% of MVC. 4. The reflex component (total minus intrinsic stiffness) had a maximum of 0.5-1.5 N.m/deg at 30-50% of MVC and was approximately zero at no and maximal contraction. For intermediate levels of contraction the reflex increased the stiffness with 40-100% of the intrinsic stiffness in this flexor muscle. 5. The reflex contribution to total stiffness began approximately 50 ms after onset of stretch and peaked 150-300 ms after onset of stretch. 6. Total, intrinsic, and reflex mediated stiffness were all nearly independent of the amplitude of stretch in the range from 2 to 7 degrees. The higher stiffness observed for 1 degree stretches could be due to "short range stiffness" of the cross bridges. 7. Stretching of a contracting muscle generates large force increments even for moderate amplitudes of stretch. Approximately half of this force increment is due to the stretch reflex, which makes the muscle stiffer than predicted from the intrinsic stiffness. These findings in human flexor muscles are surprisingly similar to previous findings in extensor muscles of the decerebrate cat.

Adult↗
PubMed1988

Effect of daunorubicin on subcellular pools of glutathione in cultured heart cells from neonatal rats.

Alterations in cellular GSH and its compartmentation were investigated as a possible mechanism of toxicity of the anthracycline derivative daunorubicin in neonatal heart cells. Cultured beating heart cells from neonatal rats were exposed to daunorubicin at therapeutically relevant concentrations and the resulting changes in cellular GSH as well as cytosolic and mitochondrial pools of GSH were determined. Toxicity was estimated as an increased permeability of the plasma membrane to cytosolic enzymes, e.g., lactate dehydrogenase. Control heart cells were found to contain 12.2 +/- 1.8 nmoles GSH/10(6) cells. Daunorubicin caused a rapid initial decrease followed by a transient increase in cellular GSH. The extent of the latter increase was dependent on the concentration of daunorubicin. High concentrations of daunorubicin gave only a slight increase followed by a pronounced decrease in cellular GSH. By applying a digitonin-based method the effect of daunorubicin on the cytosolic and mitochondrial pools of GSH were separated. The concentration of cytosolic and mitochondrial reduced GSH was estimated to be 8.9 +/- 1.5 nmoles/10(6) cells and 3.3 +/- 0.6 nmoles/10(6) cells, respectively. The results indicate that daunorubicin caused a decrease of cytosolic GSH and, after a short lag period, a release of alctate dehydrogenase. No decrease of mitochondrial GSH occurred under these conditions indicating that daunorubicin influences selectively cytosolic GSH. No lipid peroxidation products were detected in DRB-treated cells under conditions when lactate dehydrogenase was released. Likewise, addition of the iron-chelator desferrioxamin did not influence the release of lactate dehydrogenase, whereas dithiothreitol offered partial protection.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

[Pyomyositis].

Explore the source record for details and available documents.

Adult↗
PubMedDate not supplied

Passive tension of the ankle before and after stretching.

The passive tension resulting from dorsiflexion of the ankle was measured in relation to stretching in six handball players and six soccer players. Corresponding values of ankle angle and passive tension were measured by a strain gauge and a potentiometer connected to a pedal system. The passive tension versus ankle angle was measured before and 90 minutes after a single contract-relax stretching program of the plantar flexors. Stretching lowered the passive tension by up to 18%. Contract-relax stretching performed twice a day for 3 weeks lowered the passive tension in the plantar flexors by up to 36%. Before the last measurements, no stretching was performed for 20 hours or more. Stretching thus had both a short-term effect, matching the length of a training session, and a long-term effect, shown in a reduction of passive tension after 3 weeks. The relative decrease in passive tension after stretching exercises was constant from a neutral position of the ankle to maximal dorsiflexion. There was no correlation between 1) flexibility and the short-term effect of stretching, 2) flexibility and the long-term effect of stretching, or 3) the short-term and long-term effects of stretching. This indicates that passive tension was decreased in all subjects irrespective of their flexibility, and that subjects who had short-term effects after stretching did not necessarily demonstrate a long-term effect.

Adult↗